Help! :( It's on the chair seat...anyone have ideas for me?

Oxyclean???

I think you might be okay if you clean the entire seat. It won't show water spotting that way.

Research online what is the best thing to take chocolate stains out. I would probably try just some dishwashing liquid in water first, but that is me. Scrape off any excess chocolate that you can first -- maybe using a sharp knife.

I have some silk chair seats, and the dishwashing liquid in water has worked on them so far (although not for chocolate). Since the fabric is stretched, you don't have to worry about shrinkage or distortion; the stretching will prevent the fibers from crinkling up on you. I do have to treat the whole chair seat, though, even if it's just a small spot.

Worst case, I always figure I can re-cover all of the chair seats to match. My dh could take them off, and then it's just a matter of stapling fabric over existing fabric before putting them back.